Function prependTokenToDependencyPath

packages/core/src/render3/errors_di.ts:85–105

(
  error: any,
  token: ProviderToken<unknown> | {multi: true; provide: ProviderToken<unknown>},
)

 * @param token Extra token that should be appended.
 */
export function prependTokenToDependencyPath(
  error: any,
  token: ProviderToken<unknown> | {multi: true; provide: ProviderToken<unknown>},
): void {
  error[NG_TOKEN_PATH] ??= [];
  // Append current token to the current token path. Since the error
  // is bubbling up, add the token in front of other tokens.
  const currentPath = error[NG_TOKEN_PATH];
  // Do not append the same token multiple times.
  let pathStr: string;
  if (typeof token === 'object' && 'multi' in token && token?.multi === true) {
    assertDefined(token.provide, 'Token with multi: true should have a provide property');
    pathStr = stringifyForError(token.provide);
  } else {
    pathStr = stringifyForError(token);
  }

  if (currentPath[0] !== pathStr) {
    (error[NG_TOKEN_PATH] as string[]).unshift(pathStr);
  }
}

/**
 * Modifies an Error instance with an updated error message